/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xpath.axes;

import wx.xml.xalan.xml.dtm.DTM;
import wx.xml.xalan.xml.dtm.DTMFilter;
import wx.xml.xalan.xpath.Expression;
import wx.xml.xalan.xpath.compiler.Compiler;
import wx.xml.xalan.xpath.compiler.OpMap;

/**
 * This class implements a general iterator for
 * those LocationSteps with only one step, and perhaps a predicate,
 * that only go forward (i.e. it can not be used with ancestors,
 * preceding, etc.)
 *
 * @xsl.usage advanced
 * @see wx.xml.xalan.xpath.axes#ChildTestIterator
 */
public class OneStepIteratorForward extends ChildTestIterator {
    static final long serialVersionUID = -1576936606178190566L;
    /**
     * The traversal axis from where the nodes will be filtered.
     */
    protected    int  m_axis           = -1;

    /**
     * Create a OneStepIterator object.
     *
     * @param compiler A reference to the Compiler that contains the op map.
     * @param opPos    The position within the op map, which contains the
     *                 location path expression for this itterator.
     * @throws javax.xml.transform.TransformerException
     */
    OneStepIteratorForward(Compiler compiler, int opPos, int analysis)
        throws javax.xml.transform.TransformerException {
        super(compiler, opPos, analysis);
        int firstStepPos = OpMap.getFirstChildPos(opPos);

        m_axis = WalkerFactory.getAxisFromStep(compiler, firstStepPos);

    }

    /**
     * Create a OneStepIterator object that will just traverse the self axes.
     *
     * @param axis One of the wx.xml.xalan.xml.dtm.Axis integers.
     * @throws javax.xml.transform.TransformerException
     */
    public OneStepIteratorForward(int axis) {
        super(null);

        m_axis = axis;
        int whatToShow = DTMFilter.SHOW_ALL;
        initNodeTest(whatToShow);
    }


    /**
     * Initialize the context values for this expression
     * after it is cloned.
     *
     * @param context The XPath runtime context for this
     *                transformation.
     */
    public void setRoot(int context, Object environment) {
        super.setRoot(context, environment);
        m_traverser = m_cdtm.getAxisTraverser(m_axis);

    }

//  /**
//   * Return the first node out of the nodeset, if this expression is 
//   * a nodeset expression.  This is the default implementation for 
//   * nodesets.
//   * <p>WARNING: Do not mutate this class from this function!</p>
//   * @param xctxt The XPath runtime context.
//   * @return the first node out of the nodeset, or DTM.NULL.
//   */
//  public int asNode(XPathContext xctxt)
//    throws javax.xml.transform.TransformerException
//  {
//    if(getPredicateCount() > 0)
//      return super.asNode(xctxt);
//      
//    int current = xctxt.getCurrentNode();
//    
//    DTM dtm = xctxt.getDTM(current);
//    DTMAxisTraverser traverser = dtm.getAxisTraverser(m_axis);
//    
//    String localName = getLocalName();
//    String namespace = getNamespace();
//    int what = m_whatToShow;
//    
//    // System.out.println("what: ");
//    // NodeTest.debugWhatToShow(what);
//    if(DTMFilter.SHOW_ALL == what
//       || ((DTMFilter.SHOW_ELEMENT & what) == 0)
//       || localName == NodeTest.WILD
//       || namespace == NodeTest.WILD)
//    {
//      return traverser.first(current);
//    }
//    else
//    {
//      int type = getNodeTypeTest(what);
//      int extendedType = dtm.getExpandedTypeID(namespace, localName, type);
//      return traverser.first(current, extendedType);
//    }
//  }

    /**
     * Get the next node via getFirstAttribute && getNextAttribute.
     */
    protected int getNextNode() {
        m_lastFetched = (DTM.NULL == m_lastFetched)
                        ? m_traverser.first(m_context)
                        : m_traverser.next(m_context, m_lastFetched);
        return m_lastFetched;
    }

    /**
     * Returns the axis being iterated, if it is known.
     *
     * @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple
     * types.
     */
    public int getAxis() {
        return m_axis;
    }

    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr) {
        if (!super.deepEquals(expr))
            return false;

        if (m_axis != ((OneStepIteratorForward) expr).m_axis)
            return false;

        return true;
    }


}
